code: def _list_outputs(self):
      outputs = self._outputs().get()
      outputs["brain_mask"] = self._brain_mask_path
      return outputs
  
imports: import os
  import nibabel
  import numpy
  from ...utils.filemanip import split_filename, fname_presuffix
  from .base import NipyBaseInterface, have_nipy
  from ..base import TraitedSpec, traits, BaseInterfaceInputSpec, isdefined, File, InputMultiPath, OutputMultiPath
label_desc: Use image node_id 2 for calling the ComputeMask obj's underlying member method code with example usage: obj._list_outputs() and returns: outputs